Aquinas

Eleonore Stump

• Publisher: Routledge
• Year: 2008
• ISBN:
  9781134971077
• Edition: 1
• Topic: Filosofia
• Subtopic: Storia e teoria della filosofia

Few philosophers or theologians exerted as much influence on the shape of medieval thought as Thomas Aquinas. He ranks amongst the most famous of the Western philosophers and was responsible for almost single-handedly bringing the philosophy of Aristotle into harmony with Christianity. He was also one of the first philosophers to argue that philosophy and theology could support each other. The shape of metaphysics, theology, and Aristotelian thought today still bears the imprint of Aquinas' work.In this extensive and deeply researched study, Eleonore Stump examines Aquinas' major works, Summa Theologiae and Summa Contra Gentiles, and clearly assesses the vast range of Aquinas' thought. Philosophers, theologians, and students of the medieval period alike will find this unrivalled study an indispensable resource in researching and teaching Aquinas.

Part I: THE ULTIMATE FOUNDATION OF REALITY

1: METAPHYSICS A theory of things

Introduction

Obviously, one cannot do justice even to a few parts of Aquinas’s metaphysics in a single chapter,¹ but I want to lay out roughly here the main elements of what might be called ‘Aquinas’s theory of things’. This is not the same as his ontology or his theory of what there is in the world, since he supposes that being – what there is – is spread over all the ten Aristotelian categories and not just the category of substance, which includes things. It is not the same as his theory of substance either, however, since it is arguable that not everything he recognizes as a thing counts for him as a substance.² For the purposes of this chapter, I will take things to include not only substances and artifacts but also at least some of the parts of which substances are constituted. By ‘parts’ in this context, I mean both what Aquinas called ‘integral parts’, such as the hand of a human being or the roof of a house, and also metaphysical parts, such as matter and form, which constitute material things in a way different from the way they are constituted by their integral parts.³ In order to understand Aquinas’s basic worldview, it is important to understand his theory of things, and especially his view of what it is for something to be one thing.

Aside from the fact that it is complicated and technical, Aquinas’s theory of things is difficult to understand for at least two reasons. First, it makes use of Latin terms whose English equivalents are common terms in contemporary philosophy; but the meanings of the Latin terms and their English equivalents are not invariably identical.⁴ Special care is therefore necessary with the technical terminology if confusion is not to be introduced into the interpretation of Aquinas. Second, on many of the key issues of Aquinas’s metaphysics, contemporary metaphysics is itself at least contentious. (A cursory review of the contemporary literature on the nature of the constitution relation, for example, or on the nature of persistence through time illustrates the point.) We are accustomed, however, to explaining something by transposing what is obscure in it into something that is clearer to us; and we often clarify obscure views from other historical periods by mapping them on to something in contemporary views which we feel we understand better. But so much in contemporary metaphysics is not clear, at least not clear to those other than the proponents of the contemporary view in question, that this ordinary method of introducing clarity into the interpretation of historical philosophical positions is not readily available for medieval metaphysics.

For these reasons, even if there were no difficulties in Aquinas’s metaphysics itself, an insistence on a complete and consistent explanation of Aquinas’s theory of things would be likely to yield a position that is unfaithful to Aquinas’s thought, and an attempt to be faithful to his thought is likely to yield a theory that strikes us as unsatisfactory with regard to completeness or consistency. Perhaps the best that can be done in these circumstances is to narrow the gap between his way of understanding metaphysics and our own.

Matter and form

Aquinas thinks that some things are made out of matter and other things (such as angels) are not. It is easiest to approach his theory of things by beginning with his views about things made out of matter. A macro-level material thing is matter organized or configured in some way, where the organization or configuration is dynamic rather than static. That is, the organization of the matter includes causal relations among the material components of the thing as well as such static features as shape and spatial location. This dynamic configuration or organization is what Aquinas calls ‘form’.⁵ A thing has the properties it has, including its causal powers, in virtue of having the configuration it does; the proper operations and functions of a thing derive from its form.⁶ (I am here thus making a conceptual distinction between the organization of a thing and the properties the thing has in virtue of being organized in that way, and in what follows I will sometimes speak of a form’s conferring certain properties on the whole it configures.)

Like many contemporary philosophers, Aquinas recognizes levels of organization. What counts as matter for a macro-level object may itself be organized or configured in a certain way; that is, the matter of a thing may itself be constituted of matter and form.⁷

A typical medieval example given to illustrate the matter/form distinction is a bronze statue, but for our purposes here it will be more helpful to take a contemporary example. So consider the protein called ‘CAT/Enhancer-Binding Protein’ (C/EBP), one of the proteins known to play an important role in regulating gene expression.⁸ In its active form, the molecule is a dimer with an alpha helix coil. On Aquinas’s way of thinking about material objects, the form of C/EBP is the configuration of the dimer, including the alpha helix coil; and the dimer subunits constitute the matter. Of course, each dimer subunit is itself a composite. The form of the subunit is the configuration of its amino acids, in which, for example, in one region every seventh spot must be occupied by leucine; and the amino acids composing the subunit are its matter. Amino acids themselves are also clearly composites, however. The matter of an amino acid such as leucine is the carbon, hydrogen, nitrogen and oxygen of which it is composed, and the form is the way that material is combined, including the characteristic NH₂ configuration common to all the amino acids and the sequence of carbon and hydrogen peculiar to leucine. We can evidently go on in this way until we come, for example, to the proton of a hydrogen atom. The quarks that compose it are its matter, and their configuration – the right combination of and interactions between up and down quarks – is the form of the proton. But at some point this process of moving down the levels of organization of a macro-level thing must come to a halt. For Aquinas, the lowest-level material component which counts as matter organized in a certain way is an element.⁹ An element is constituted of matter and form, but if we conceptually strip away the form or configuration of an element, all that remains is prime matter; matter which cannot itself be decomposed further into matter and form.

Prime matter is thus matter without any form at all, “materiality” (as it were) apart from configuration. When it is a component in a matter-form composite, prime matter is the component of the configured composite which makes it the case that the configured thing can be extended in three dimensions and can occupy a particular place at a particular time. But by itself, apart from form, prime matter exists just potentially; it exists in actuality only as an ingredient in something configured.¹⁰ So we can remove form from prime matter only in thought; everything which exists in reality is configured in some way. For this reason, Aquinas sometimes says that form is the actuality of anything.¹¹ Configuration or organization is necessary for the existence of anything at all; without form, nothing is actual.

This point holds also for immaterial things. For Aquinas, there are things that exist and are organized in a certain way, but the organization is not an organization of matter. An angel, a certain kind of intelligence, is an example. An angel has no matter to configure, but it is nonetheless configured in a certain way. It has certain properties, such as being a knower, and not others, such as weighing two hundred pounds. And so there is a kind of organization in an angel, too, which we can think of as an organization of properties. An angel has one constellation of properties rather than another, and in virtue of these properties it also has one set of causal powers rather than another.¹²

Consequently, although matter is not necessary for the existence of a thing, on Aquinas’s view, form is. For Aquinas, to be is to be configured.

Substantial and accidental forms

Aquinas takes it that the forms of material objects can be divided into two sorts, substantial forms (that is, the substantial forms of primary substances) and accidental forms. (Immaterial things can also have both substantial and accidental forms, but in the discussion which follows, for the sake of simplicity, my focus will be just on that part of Aquinas’s theory of things which has to do with things made of matter.¹³) For present purposes we can understand his distinction between these two sorts of forms roughly in this way. The difference between the substantial and the accidental forms of material objects is a function of three things: (1) what the form organizes or configures; (2) what the configuration effects; and (3) what kind of change is produced by the advent of the configuration.

Regarding (1): a substantial form of a material thing configures prime matter. An accidental form, on the other hand, configures something which is an actually existing complete thing, a matter-form composite.¹⁴ Or to put the same point in a different way, if we conceptually strip away a substantial form from a material thing (and don’t immediately replace it with another substantial form of some sort), what is left cannot exist in actuality. Nothing that is actual consists only of prime matter plus accidental properties. But if we strip away any particular accidental form, what is left is still an actually existing complete thing, and it remains the same complete thing it was before the accidental form was stripped away. (On the other hand, it is not possible to strip away all accidental forms from a material thing. It is necessary to a material thing that it have accidental forms, even if it is not necessary that it have one rather than another accidental form.)

Regarding (2): for this reason, configuration by a substantial form brings it about that a thing which was not already in existence comes into existence. Since any thing that comes into existence exists as a member of a kind, the substantial form of a thing is thus also responsible for a thing’s belonging to a particular primary kind or lowest species. On Aquinas’s views, every substance is a member of exactly one lowest species or primary kind, although species can be ordered hierarchically under genera, which can themselves be ordered hierarchically under higher genera until one comes to the highest genus, which is substance. Configuration by an accidental form, on the other hand, brings it about only that an already existing thing comes to have a certain property, without ceasing to be the thing (or the kind of thing) it was.¹⁵ Accidental forms are thus responsible for the non-essential properties of a thing; the addition or removal of an accidental form does not alter the species to which the whole belongs or the identity of the whole.¹⁶

Regarding (3): the change produced by the advent of a substantial form is therefore a generation of a thing. The change produced by the advent of an accidental form, by contrast, is only an alteration of one and the same thing.¹⁷

It is clear from these claims that any material thing which exists has a substantial form. But Aquinas’s claims about substantial form also imply that no existing material thing has more than one substantial form.¹⁸ A composite which consists of prime matter configured by a substantial form could not itself be one component among others of a larger whole configured by yet another substantial form. That is because a substantial form of a material thing configures prime matter; but if a substantial form were to configure what is already configured by a substantial form, then it would be configuring a matter-form composite, not prime matter. (Of course, the new substantial form might simply replace the previous one, but in that case the composite would still be configured by only one substantial form.)

Furthermore, Aquinas’s claims about substantial forms limit the way in which already existing things can be combined into a composite substance. Barnacles have a substantial form, and so do starfish. If a barnacle attaches itself very firmly to the back of a starfish, that attaching will not constitute a generation of a substance. If it did, there would be one thing – the barnacle–starfish composite – which had more than one substantial form, the form of the barnacle and the form of the starfish.¹⁹ So what the attachment of the barnacle to the starfish effects, on Aquinas’s views, is just that two complete things come to have a property or properties which they did not have before, as, for example, the property of being fastened together. The new configuration of the barnacle attached to the starfish will thus be an accidental one. Any case in which two already existing material things come together into some kind of composite without ceasing to exist as the things they were before they came together will similarly be a case of alteration rather than generation, and the new composite will be configured with an accidental, rather than a substantial, form.²⁰

Any ordinary artifact is configured only with an accidental form. The production of an artifact, such as an axe with a metal blade attached to a wooden handle, brings together already existing things – a metal thing and a wooden thing – which in the new composite still remain the things they were before being conjoined. An artifact is thus a composite of things configured together into a whole but not by a substantial form.²¹ Since only something configured by a substantial form is a substance, no artifact is a substance.

Substances and artifacts

Elements – earth, air, fire and water – are substances, and so is a material made of one element.²² Furthermore, different elements can combine to form a compound which is itself a substance.²³ So, for example, earth and fire can combine to form flesh. But they can do so only when the substantial form of each combining element is lost in the composite and is replaced by the one substantial form of the whole compound.²⁴ Furthermore, the substances which are compounds of elements, such as flesh or blood, can combine into one thing, such as an animal, only when they also are not substances in their own right in the newly composed whole.²⁵ On Aquinas’s view, the parts of a whole are actua...